Ionic mechanisms and synaptic interactions in the vertebrate retina will be studied in the perfused mammalian and amphibian eyecup preparation. Intracellular recording and ion replacement studies will be combined with ion specific electrode application and voltage clamp experiments. The ionic mechanisms of light evoked neuronal activity will be related to the Muller (glial) cell responses which contribute to the electro retinogram (ERG). BIBLIOGRAPHIC REFERENCES: Miller, R.F. and R.F. Dacheux. Chloride-sensitive receptive field mechanisms in the isolated retina-eyecup of the rabbit. Brain Res. 90, 329-334, 1975.